Rare diseases · Sign or symptom

Hypertonia

HP:0001276

What it means

A condition in which there is increased muscle tone so that arms or legs, for example, are stiff and difficult to move.

Spasticity is a term that is often used interchangeably with hypertonia. Spasticity, however, is a particular type of hypertonia in which the muscles' spasms are increased by movement. In this type, patients usually have exaggerated reflex responses.

Rare diseases that can present with this168

Very common80–99%

35

Common30–79%

44

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Hypertonicity · Increased muscle tone · Muscle hypertonia · Spasticity and rigidity of muscles

Hypertonia

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This page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.